3-Phase Servo AVR (AC Voltage Stabilizer) — Parts, Tests, Repair & Maintenance

 

Resistor Color Coding

The resistor color coding system is a method used to indicate the resistance value, tolerance, and sometimes reliability of resistors using colored bands printed on the component. The system typically uses 4-band, 5-band, or 6-band color codes.

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1. Color Code Table

The colors represent numbers, multipliers, and tolerances as shown below:

Color	Digit	Multiplier (Ω)	Tolerance (%)
Black	0	×1	-
Brown	1	×10	±1
Red	2	×100	±2
Orange	3	×1,000 (1kΩ)	-
Yellow	4	×10,000 (10kΩ)	-
Green	5	×100,000 (100kΩ)	±0.5
Blue	6	×1,000,000 (1MΩ)	±0.25
Violet	7	×10,000,000 (10MΩ)	±0.1
Gray	8	×100,000,000	±0.05
White	9	×1,000,000,000	-
Gold	-	×0.1	±5
Silver	-	×0.01	±10
None	-	-	±20

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2. Resistor Types Based on Bands

4-Band Resistors

• Structure: 3 color bands for resistance value and 1 for tolerance.
• Calculation:
  • First and second bands = significant digits.
  • Third band = multiplier.
  • Fourth band = tolerance.

Example:
A resistor with bands Brown, Black, Red, and Gold:

• Brown = 1, Black = 0 → Significant digits = 10.
• Red = ×100 → Resistance = 10 × 100 = 1,000 Ω (1kΩ).
• Gold = ±5% → Tolerance = ±5%.

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5-Band Resistors

• Structure: 3 color bands for resistance value, 1 for multiplier, and 1 for tolerance.
• Calculation:
  • First three bands = significant digits.
  • Fourth band = multiplier.
  • Fifth band = tolerance.

Example:
A resistor with bands Brown, Green, Black, Red, and Brown:

• Brown = 1, Green = 5, Black = 0 → Significant digits = 150.
• Red = ×100 → Resistance = 150 × 100 = 15,000 Ω (15kΩ).
• Brown = ±1% → Tolerance = ±1%.

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6-Band Resistors

• Structure: 3 color bands for resistance value, 1 for multiplier, 1 for tolerance, and 1 for temperature coefficient (ppm/°C).
• Calculation:
  • First three bands = significant digits.
  • Fourth band = multiplier.
  • Fifth band = tolerance.
  • Sixth band = temperature coefficient.

Example:
A resistor with bands Red, Violet, Yellow, Brown, Gold, and Blue:

• Red = 2, Violet = 7, Yellow = 4 → Significant digits = 274.
• Brown = ×10 → Resistance = 274 × 10 = 2,740 Ω (2.74kΩ).
• Gold = ±5% → Tolerance = ±5%.
• Blue = 10ppm/°C → Temperature coefficient = 10ppm/°C.

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3. Diagram of Resistor Bands

    +-----------------------------------------------------+
    | Band 1 | Band 2 | Band 3 | Band 4 | Band 5 | Band 6 |
    +-----------------------------------------------------+
    | Digit 1| Digit 2| Multiplier | Tolerance | Temp Coeff|

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4. Example Resistor with Color Bands

4-Band Example

5-Band Example

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5. Tips for Reading Resistor Values

1. Identify Orientation: Start from the end closest to a band (usually tolerance is the last band).
2. Use the Color Table: Refer to the table for digits, multipliers, and tolerances.
3. Cross-Check Values: Verify calculated resistance with a multimeter.

Let me know if you need further assistance!